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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [gcc/] [cp/] [cvt.c] - Blame information for rev 298

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1 283 jeremybenn
/* Language-level data type conversion for GNU C++.
2
   Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3
   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4
   Free Software Foundation, Inc.
5
   Hacked by Michael Tiemann (tiemann@cygnus.com)
6
 
7
This file is part of GCC.
8
 
9
GCC is free software; you can redistribute it and/or modify
10
it under the terms of the GNU General Public License as published by
11
the Free Software Foundation; either version 3, or (at your option)
12
any later version.
13
 
14
GCC is distributed in the hope that it will be useful,
15
but WITHOUT ANY WARRANTY; without even the implied warranty of
16
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17
GNU General Public License for more details.
18
 
19
You should have received a copy of the GNU General Public License
20
along with GCC; see the file COPYING3.  If not see
21
<http://www.gnu.org/licenses/>.  */
22
 
23
 
24
/* This file contains the functions for converting C++ expressions
25
   to different data types.  The only entry point is `convert'.
26
   Every language front end must have a `convert' function
27
   but what kind of conversions it does will depend on the language.  */
28
 
29
#include "config.h"
30
#include "system.h"
31
#include "coretypes.h"
32
#include "tm.h"
33
#include "tree.h"
34
#include "flags.h"
35
#include "cp-tree.h"
36
#include "intl.h"
37
#include "convert.h"
38
#include "toplev.h"
39
#include "decl.h"
40
#include "target.h"
41
 
42
static tree cp_convert_to_pointer (tree, tree);
43
static tree convert_to_pointer_force (tree, tree);
44
static tree build_type_conversion (tree, tree);
45
static tree build_up_reference (tree, tree, int, tree);
46
static void warn_ref_binding (tree, tree, tree);
47
 
48
/* Change of width--truncation and extension of integers or reals--
49
   is represented with NOP_EXPR.  Proper functioning of many things
50
   assumes that no other conversions can be NOP_EXPRs.
51
 
52
   Conversion between integer and pointer is represented with CONVERT_EXPR.
53
   Converting integer to real uses FLOAT_EXPR
54
   and real to integer uses FIX_TRUNC_EXPR.
55
 
56
   Here is a list of all the functions that assume that widening and
57
   narrowing is always done with a NOP_EXPR:
58
     In convert.c, convert_to_integer.
59
     In c-typeck.c, build_binary_op_nodefault (boolean ops),
60
        and c_common_truthvalue_conversion.
61
     In expr.c: expand_expr, for operands of a MULT_EXPR.
62
     In fold-const.c: fold.
63
     In tree.c: get_narrower and get_unwidened.
64
 
65
   C++: in multiple-inheritance, converting between pointers may involve
66
   adjusting them by a delta stored within the class definition.  */
67
 
68
/* Subroutines of `convert'.  */
69
 
70
/* if converting pointer to pointer
71
     if dealing with classes, check for derived->base or vice versa
72
     else if dealing with method pointers, delegate
73
     else convert blindly
74
   else if converting class, pass off to build_type_conversion
75
   else try C-style pointer conversion.  */
76
 
77
static tree
78
cp_convert_to_pointer (tree type, tree expr)
79
{
80
  tree intype = TREE_TYPE (expr);
81
  enum tree_code form;
82
  tree rval;
83
  if (intype == error_mark_node)
84
    return error_mark_node;
85
 
86
  if (MAYBE_CLASS_TYPE_P (intype))
87
    {
88
      intype = complete_type (intype);
89
      if (!COMPLETE_TYPE_P (intype))
90
        {
91
          error ("can't convert from incomplete type %qT to %qT",
92
                 intype, type);
93
          return error_mark_node;
94
        }
95
 
96
      rval = build_type_conversion (type, expr);
97
      if (rval)
98
        {
99
          if (rval == error_mark_node)
100
            error ("conversion of %qE from %qT to %qT is ambiguous",
101
                   expr, intype, type);
102
          return rval;
103
        }
104
    }
105
 
106
  /* Handle anachronistic conversions from (::*)() to cv void* or (*)().  */
107
  if (TREE_CODE (type) == POINTER_TYPE
108
      && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
109
          || VOID_TYPE_P (TREE_TYPE (type))))
110
    {
111
      if (TYPE_PTRMEMFUNC_P (intype)
112
          || TREE_CODE (intype) == METHOD_TYPE)
113
        return convert_member_func_to_ptr (type, expr);
114
      if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
115
        return build_nop (type, expr);
116
      intype = TREE_TYPE (expr);
117
    }
118
 
119
  if (expr == error_mark_node)
120
    return error_mark_node;
121
 
122
  form = TREE_CODE (intype);
123
 
124
  if (POINTER_TYPE_P (intype))
125
    {
126
      intype = TYPE_MAIN_VARIANT (intype);
127
 
128
      if (TYPE_MAIN_VARIANT (type) != intype
129
          && TREE_CODE (type) == POINTER_TYPE
130
          && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
131
          && MAYBE_CLASS_TYPE_P (TREE_TYPE (type))
132
          && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype))
133
          && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
134
        {
135
          enum tree_code code = PLUS_EXPR;
136
          tree binfo;
137
          tree intype_class;
138
          tree type_class;
139
          bool same_p;
140
 
141
          intype_class = TREE_TYPE (intype);
142
          type_class = TREE_TYPE (type);
143
 
144
          same_p = same_type_p (TYPE_MAIN_VARIANT (intype_class),
145
                                TYPE_MAIN_VARIANT (type_class));
146
          binfo = NULL_TREE;
147
          /* Try derived to base conversion.  */
148
          if (!same_p)
149
            binfo = lookup_base (intype_class, type_class, ba_check, NULL);
150
          if (!same_p && !binfo)
151
            {
152
              /* Try base to derived conversion.  */
153
              binfo = lookup_base (type_class, intype_class, ba_check, NULL);
154
              code = MINUS_EXPR;
155
            }
156
          if (binfo == error_mark_node)
157
            return error_mark_node;
158
          if (binfo || same_p)
159
            {
160
              if (binfo)
161
                expr = build_base_path (code, expr, binfo, 0);
162
              /* Add any qualifier conversions.  */
163
              return build_nop (type, expr);
164
            }
165
        }
166
 
167
      if (TYPE_PTRMEMFUNC_P (type))
168
        {
169
          error ("cannot convert %qE from type %qT to type %qT",
170
                 expr, intype, type);
171
          return error_mark_node;
172
        }
173
 
174
      return build_nop (type, expr);
175
    }
176
  else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
177
           || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
178
    return convert_ptrmem (type, expr, /*allow_inverse_p=*/false,
179
                           /*c_cast_p=*/false);
180
  else if (TYPE_PTRMEMFUNC_P (intype))
181
    {
182
      if (!warn_pmf2ptr)
183
        {
184
          if (TREE_CODE (expr) == PTRMEM_CST)
185
            return cp_convert_to_pointer (type,
186
                                          PTRMEM_CST_MEMBER (expr));
187
          else if (TREE_CODE (expr) == OFFSET_REF)
188
            {
189
              tree object = TREE_OPERAND (expr, 0);
190
              return get_member_function_from_ptrfunc (&object,
191
                                                       TREE_OPERAND (expr, 1));
192
            }
193
        }
194
      error ("cannot convert %qE from type %qT to type %qT",
195
             expr, intype, type);
196
      return error_mark_node;
197
    }
198
 
199
  if (integer_zerop (expr))
200
    {
201
      if (TYPE_PTRMEMFUNC_P (type))
202
        return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0,
203
                                 /*c_cast_p=*/false);
204
 
205
      if (TYPE_PTRMEM_P (type))
206
        {
207
          /* A NULL pointer-to-member is represented by -1, not by
208
             zero.  */
209
          expr = build_int_cst_type (type, -1);
210
        }
211
      else
212
        expr = build_int_cst (type, 0);
213
 
214
      return expr;
215
    }
216
  else if (TYPE_PTR_TO_MEMBER_P (type) && INTEGRAL_CODE_P (form))
217
    {
218
      error ("invalid conversion from %qT to %qT", intype, type);
219
      return error_mark_node;
220
    }
221
 
222
  if (INTEGRAL_CODE_P (form))
223
    {
224
      if (TYPE_PRECISION (intype) == POINTER_SIZE)
225
        return build1 (CONVERT_EXPR, type, expr);
226
      expr = cp_convert (c_common_type_for_size (POINTER_SIZE, 0), expr);
227
      /* Modes may be different but sizes should be the same.  There
228
         is supposed to be some integral type that is the same width
229
         as a pointer.  */
230
      gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
231
                  == GET_MODE_SIZE (TYPE_MODE (type)));
232
 
233
      return convert_to_pointer (type, expr);
234
    }
235
 
236
  if (type_unknown_p (expr))
237
    return instantiate_type (type, expr, tf_warning_or_error);
238
 
239
  error ("cannot convert %qE from type %qT to type %qT",
240
         expr, intype, type);
241
  return error_mark_node;
242
}
243
 
244
/* Like convert, except permit conversions to take place which
245
   are not normally allowed due to access restrictions
246
   (such as conversion from sub-type to private super-type).  */
247
 
248
static tree
249
convert_to_pointer_force (tree type, tree expr)
250
{
251
  tree intype = TREE_TYPE (expr);
252
  enum tree_code form = TREE_CODE (intype);
253
 
254
  if (form == POINTER_TYPE)
255
    {
256
      intype = TYPE_MAIN_VARIANT (intype);
257
 
258
      if (TYPE_MAIN_VARIANT (type) != intype
259
          && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
260
          && MAYBE_CLASS_TYPE_P (TREE_TYPE (type))
261
          && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype))
262
          && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
263
        {
264
          enum tree_code code = PLUS_EXPR;
265
          tree binfo;
266
 
267
          binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
268
                               ba_unique, NULL);
269
          if (!binfo)
270
            {
271
              binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
272
                                   ba_unique, NULL);
273
              code = MINUS_EXPR;
274
            }
275
          if (binfo == error_mark_node)
276
            return error_mark_node;
277
          if (binfo)
278
            {
279
              expr = build_base_path (code, expr, binfo, 0);
280
              if (expr == error_mark_node)
281
                 return error_mark_node;
282
              /* Add any qualifier conversions.  */
283
              if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
284
                                TREE_TYPE (type)))
285
                expr = build_nop (type, expr);
286
              return expr;
287
            }
288
        }
289
    }
290
 
291
  return cp_convert_to_pointer (type, expr);
292
}
293
 
294
/* We are passing something to a function which requires a reference.
295
   The type we are interested in is in TYPE. The initial
296
   value we have to begin with is in ARG.
297
 
298
   FLAGS controls how we manage access checking.
299
   DIRECT_BIND in FLAGS controls how any temporaries are generated.
300
     If DIRECT_BIND is set, DECL is the reference we're binding to.  */
301
 
302
static tree
303
build_up_reference (tree type, tree arg, int flags, tree decl)
304
{
305
  tree rval;
306
  tree argtype = TREE_TYPE (arg);
307
  tree target_type = TREE_TYPE (type);
308
 
309
  gcc_assert (TREE_CODE (type) == REFERENCE_TYPE);
310
 
311
  if ((flags & DIRECT_BIND) && ! real_lvalue_p (arg))
312
    {
313
      /* Create a new temporary variable.  We can't just use a TARGET_EXPR
314
         here because it needs to live as long as DECL.  */
315
      tree targ = arg;
316
 
317
      arg = make_temporary_var_for_ref_to_temp (decl, TREE_TYPE (arg));
318
 
319
      /* Process the initializer for the declaration.  */
320
      DECL_INITIAL (arg) = targ;
321
      cp_finish_decl (arg, targ, /*init_const_expr_p=*/false, NULL_TREE,
322
                      LOOKUP_ONLYCONVERTING|DIRECT_BIND);
323
    }
324
  else if (!(flags & DIRECT_BIND) && ! lvalue_p (arg))
325
    return get_target_expr (arg);
326
 
327
  /* If we had a way to wrap this up, and say, if we ever needed its
328
     address, transform all occurrences of the register, into a memory
329
     reference we could win better.  */
330
  rval = cp_build_unary_op (ADDR_EXPR, arg, 1, tf_warning_or_error);
331
  if (rval == error_mark_node)
332
    return error_mark_node;
333
 
334
  if ((flags & LOOKUP_PROTECT)
335
      && TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type)
336
      && MAYBE_CLASS_TYPE_P (argtype)
337
      && MAYBE_CLASS_TYPE_P (target_type))
338
    {
339
      /* We go through lookup_base for the access control.  */
340
      tree binfo = lookup_base (argtype, target_type, ba_check, NULL);
341
      if (binfo == error_mark_node)
342
        return error_mark_node;
343
      if (binfo == NULL_TREE)
344
        return error_not_base_type (target_type, argtype);
345
      rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
346
    }
347
  else
348
    rval
349
      = convert_to_pointer_force (build_pointer_type (target_type), rval);
350
  return build_nop (type, rval);
351
}
352
 
353
/* Subroutine of convert_to_reference. REFTYPE is the target reference type.
354
   INTYPE is the original rvalue type and DECL is an optional _DECL node
355
   for diagnostics.
356
 
357
   [dcl.init.ref] says that if an rvalue is used to
358
   initialize a reference, then the reference must be to a
359
   non-volatile const type.  */
360
 
361
static void
362
warn_ref_binding (tree reftype, tree intype, tree decl)
363
{
364
  tree ttl = TREE_TYPE (reftype);
365
 
366
  if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl))
367
    {
368
      const char *msg;
369
 
370
      if (CP_TYPE_VOLATILE_P (ttl) && decl)
371
        msg = G_("initialization of volatile reference type %q#T from "
372
                 "rvalue of type %qT");
373
      else if (CP_TYPE_VOLATILE_P (ttl))
374
        msg = G_("conversion to volatile reference type %q#T "
375
                 "from rvalue of type %qT");
376
      else if (decl)
377
        msg = G_("initialization of non-const reference type %q#T from "
378
                 "rvalue of type %qT");
379
      else
380
        msg = G_("conversion to non-const reference type %q#T from "
381
                 "rvalue of type %qT");
382
 
383
      permerror (input_location, msg, reftype, intype);
384
    }
385
}
386
 
387
/* For C++: Only need to do one-level references, but cannot
388
   get tripped up on signed/unsigned differences.
389
 
390
   DECL is either NULL_TREE or the _DECL node for a reference that is being
391
   initialized.  It can be error_mark_node if we don't know the _DECL but
392
   we know it's an initialization.  */
393
 
394
tree
395
convert_to_reference (tree reftype, tree expr, int convtype,
396
                      int flags, tree decl)
397
{
398
  tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype));
399
  tree intype;
400
  tree rval = NULL_TREE;
401
  tree rval_as_conversion = NULL_TREE;
402
  bool can_convert_intype_to_type;
403
 
404
  if (TREE_CODE (type) == FUNCTION_TYPE
405
      && TREE_TYPE (expr) == unknown_type_node)
406
    expr = instantiate_type (type, expr,
407
                             (flags & LOOKUP_COMPLAIN)
408
                             ? tf_warning_or_error : tf_none);
409
 
410
  if (expr == error_mark_node)
411
    return error_mark_node;
412
 
413
  intype = TREE_TYPE (expr);
414
 
415
  gcc_assert (TREE_CODE (intype) != REFERENCE_TYPE);
416
  gcc_assert (TREE_CODE (reftype) == REFERENCE_TYPE);
417
 
418
  intype = TYPE_MAIN_VARIANT (intype);
419
 
420
  can_convert_intype_to_type = can_convert (type, intype);
421
  if (!can_convert_intype_to_type
422
      && (convtype & CONV_IMPLICIT) && MAYBE_CLASS_TYPE_P (intype)
423
      && ! (flags & LOOKUP_NO_CONVERSION))
424
    {
425
      /* Look for a user-defined conversion to lvalue that we can use.  */
426
 
427
      rval_as_conversion
428
        = build_type_conversion (reftype, expr);
429
 
430
      if (rval_as_conversion && rval_as_conversion != error_mark_node
431
          && real_lvalue_p (rval_as_conversion))
432
        {
433
          expr = rval_as_conversion;
434
          rval_as_conversion = NULL_TREE;
435
          intype = type;
436
          can_convert_intype_to_type = 1;
437
        }
438
    }
439
 
440
  if (((convtype & CONV_STATIC) && can_convert (intype, type))
441
      || ((convtype & CONV_IMPLICIT) && can_convert_intype_to_type))
442
    {
443
      if (flags & LOOKUP_COMPLAIN)
444
        {
445
          tree ttl = TREE_TYPE (reftype);
446
          tree ttr = lvalue_type (expr);
447
 
448
          if (! real_lvalue_p (expr))
449
            warn_ref_binding (reftype, intype, decl);
450
 
451
          if (! (convtype & CONV_CONST)
452
                   && !at_least_as_qualified_p (ttl, ttr))
453
            permerror (input_location, "conversion from %qT to %qT discards qualifiers",
454
                       ttr, reftype);
455
        }
456
 
457
      return build_up_reference (reftype, expr, flags, decl);
458
    }
459
  else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr))
460
    {
461
      /* When casting an lvalue to a reference type, just convert into
462
         a pointer to the new type and deference it.  This is allowed
463
         by San Diego WP section 5.2.9 paragraph 12, though perhaps it
464
         should be done directly (jason).  (int &)ri ---> *(int*)&ri */
465
 
466
      /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
467
         meant.  */
468
      if (TREE_CODE (intype) == POINTER_TYPE
469
          && (comptypes (TREE_TYPE (intype), type,
470
                         COMPARE_BASE | COMPARE_DERIVED)))
471
        warning (0, "casting %qT to %qT does not dereference pointer",
472
                 intype, reftype);
473
 
474
      rval = cp_build_unary_op (ADDR_EXPR, expr, 0, tf_warning_or_error);
475
      if (rval != error_mark_node)
476
        rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
477
                              rval, 0);
478
      if (rval != error_mark_node)
479
        rval = build1 (NOP_EXPR, reftype, rval);
480
    }
481
  else
482
    {
483
      rval = convert_for_initialization (NULL_TREE, type, expr, flags,
484
                                         "converting", 0, 0,
485
                                         tf_warning_or_error);
486
      if (rval == NULL_TREE || rval == error_mark_node)
487
        return rval;
488
      warn_ref_binding (reftype, intype, decl);
489
      rval = build_up_reference (reftype, rval, flags, decl);
490
    }
491
 
492
  if (rval)
493
    {
494
      /* If we found a way to convert earlier, then use it.  */
495
      return rval;
496
    }
497
 
498
  if (flags & LOOKUP_COMPLAIN)
499
    error ("cannot convert type %qT to type %qT", intype, reftype);
500
 
501
  return error_mark_node;
502
}
503
 
504
/* We are using a reference VAL for its value. Bash that reference all the
505
   way down to its lowest form.  */
506
 
507
tree
508
convert_from_reference (tree val)
509
{
510
  if (TREE_TYPE (val)
511
      && TREE_CODE (TREE_TYPE (val)) == REFERENCE_TYPE)
512
    {
513
      tree t = TREE_TYPE (TREE_TYPE (val));
514
      tree ref = build1 (INDIRECT_REF, t, val);
515
 
516
       /* We *must* set TREE_READONLY when dereferencing a pointer to const,
517
          so that we get the proper error message if the result is used
518
          to assign to.  Also, &* is supposed to be a no-op.  */
519
      TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
520
      TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
521
      TREE_SIDE_EFFECTS (ref)
522
        = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (val));
523
      REFERENCE_REF_P (ref) = 1;
524
      val = ref;
525
    }
526
 
527
  return val;
528
}
529
 
530
/* Really perform an lvalue-to-rvalue conversion, including copying an
531
   argument of class type into a temporary.  */
532
 
533
tree
534
force_rvalue (tree expr)
535
{
536
  if (MAYBE_CLASS_TYPE_P (TREE_TYPE (expr)) && TREE_CODE (expr) != TARGET_EXPR)
537
    expr = ocp_convert (TREE_TYPE (expr), expr,
538
                        CONV_IMPLICIT|CONV_FORCE_TEMP, LOOKUP_NORMAL);
539
  else
540
    expr = decay_conversion (expr);
541
 
542
  return expr;
543
}
544
 
545
 
546
/* Fold away simple conversions, but make sure the result is an rvalue.  */
547
 
548
tree
549
cp_fold_convert (tree type, tree expr)
550
{
551
  return rvalue (fold_convert (type, expr));
552
}
553
 
554
/* C++ conversions, preference to static cast conversions.  */
555
 
556
tree
557
cp_convert (tree type, tree expr)
558
{
559
  return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL);
560
}
561
 
562
/* C++ equivalent of convert_and_check but using cp_convert as the
563
   conversion function.
564
 
565
   Convert EXPR to TYPE, warning about conversion problems with constants.
566
   Invoke this function on every expression that is converted implicitly,
567
   i.e. because of language rules and not because of an explicit cast.  */
568
 
569
tree
570
cp_convert_and_check (tree type, tree expr)
571
{
572
  tree result;
573
 
574
  if (TREE_TYPE (expr) == type)
575
    return expr;
576
 
577
  result = cp_convert (type, expr);
578
 
579
  if (c_inhibit_evaluation_warnings == 0
580
      && !TREE_OVERFLOW_P (expr)
581
      && result != error_mark_node)
582
    warnings_for_convert_and_check (type, expr, result);
583
 
584
  return result;
585
}
586
 
587
/* Conversion...
588
 
589
   FLAGS indicates how we should behave.  */
590
 
591
tree
592
ocp_convert (tree type, tree expr, int convtype, int flags)
593
{
594
  tree e = expr;
595
  enum tree_code code = TREE_CODE (type);
596
  const char *invalid_conv_diag;
597
  tree e1;
598
 
599
  if (error_operand_p (e) || type == error_mark_node)
600
    return error_mark_node;
601
 
602
  complete_type (type);
603
  complete_type (TREE_TYPE (expr));
604
 
605
  if ((invalid_conv_diag
606
       = targetm.invalid_conversion (TREE_TYPE (expr), type)))
607
    {
608
      error (invalid_conv_diag);
609
      return error_mark_node;
610
    }
611
 
612
  e = integral_constant_value (e);
613
 
614
  if (MAYBE_CLASS_TYPE_P (type) && (convtype & CONV_FORCE_TEMP))
615
    /* We need a new temporary; don't take this shortcut.  */;
616
  else if (same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (e)))
617
    {
618
      if (same_type_p (type, TREE_TYPE (e)))
619
        /* The call to fold will not always remove the NOP_EXPR as
620
           might be expected, since if one of the types is a typedef;
621
           the comparison in fold is just equality of pointers, not a
622
           call to comptypes.  We don't call fold in this case because
623
           that can result in infinite recursion; fold will call
624
           convert, which will call ocp_convert, etc.  */
625
        return e;
626
      /* For complex data types, we need to perform componentwise
627
         conversion.  */
628
      else if (TREE_CODE (type) == COMPLEX_TYPE)
629
        return fold_if_not_in_template (convert_to_complex (type, e));
630
      else if (TREE_CODE (e) == TARGET_EXPR)
631
        {
632
          /* Don't build a NOP_EXPR of class type.  Instead, change the
633
             type of the temporary.  */
634
          TREE_TYPE (e) = TREE_TYPE (TARGET_EXPR_SLOT (e)) = type;
635
          return e;
636
        }
637
      else
638
        {
639
          /* We shouldn't be treating objects of ADDRESSABLE type as
640
             rvalues.  */
641
          gcc_assert (!TREE_ADDRESSABLE (type));
642
          return fold_if_not_in_template (build_nop (type, e));
643
        }
644
    }
645
 
646
  e1 = targetm.convert_to_type (type, e);
647
  if (e1)
648
    return e1;
649
 
650
  if (code == VOID_TYPE && (convtype & CONV_STATIC))
651
    {
652
      e = convert_to_void (e, /*implicit=*/NULL, tf_warning_or_error);
653
      return e;
654
    }
655
 
656
  if (INTEGRAL_CODE_P (code))
657
    {
658
      tree intype = TREE_TYPE (e);
659
 
660
      if (TREE_CODE (type) == ENUMERAL_TYPE)
661
        {
662
          /* enum = enum, enum = int, enum = float, (enum)pointer are all
663
             errors.  */
664
          if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype)
665
                || TREE_CODE (intype) == REAL_TYPE)
666
               && ! (convtype & CONV_STATIC))
667
              || TREE_CODE (intype) == POINTER_TYPE)
668
            {
669
              if (flags & LOOKUP_COMPLAIN)
670
                permerror (input_location, "conversion from %q#T to %q#T", intype, type);
671
 
672
              if (!flag_permissive)
673
                return error_mark_node;
674
            }
675
 
676
          /* [expr.static.cast]
677
 
678
             8. A value of integral or enumeration type can be explicitly
679
             converted to an enumeration type. The value is unchanged if
680
             the original value is within the range of the enumeration
681
             values. Otherwise, the resulting enumeration value is
682
             unspecified.  */
683
          if (TREE_CODE (expr) == INTEGER_CST && !int_fits_type_p (expr, type))
684
            warning (OPT_Wconversion,
685
                     "the result of the conversion is unspecified because "
686
                     "%qE is outside the range of type %qT",
687
                     expr, type);
688
        }
689
      if (MAYBE_CLASS_TYPE_P (intype))
690
        {
691
          tree rval;
692
          rval = build_type_conversion (type, e);
693
          if (rval)
694
            return rval;
695
          if (flags & LOOKUP_COMPLAIN)
696
            error ("%q#T used where a %qT was expected", intype, type);
697
          return error_mark_node;
698
        }
699
      if (code == BOOLEAN_TYPE)
700
        return cp_truthvalue_conversion (e);
701
 
702
      return fold_if_not_in_template (convert_to_integer (type, e));
703
    }
704
  if (POINTER_TYPE_P (type) || TYPE_PTR_TO_MEMBER_P (type))
705
    return fold_if_not_in_template (cp_convert_to_pointer (type, e));
706
  if (code == VECTOR_TYPE)
707
    {
708
      tree in_vtype = TREE_TYPE (e);
709
      if (MAYBE_CLASS_TYPE_P (in_vtype))
710
        {
711
          tree ret_val;
712
          ret_val = build_type_conversion (type, e);
713
          if (ret_val)
714
            return ret_val;
715
          if (flags & LOOKUP_COMPLAIN)
716
            error ("%q#T used where a %qT was expected", in_vtype, type);
717
          return error_mark_node;
718
        }
719
      return fold_if_not_in_template (convert_to_vector (type, e));
720
    }
721
  if (code == REAL_TYPE || code == COMPLEX_TYPE)
722
    {
723
      if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e)))
724
        {
725
          tree rval;
726
          rval = build_type_conversion (type, e);
727
          if (rval)
728
            return rval;
729
          else
730
            if (flags & LOOKUP_COMPLAIN)
731
              error ("%q#T used where a floating point value was expected",
732
                        TREE_TYPE (e));
733
        }
734
      if (code == REAL_TYPE)
735
        return fold_if_not_in_template (convert_to_real (type, e));
736
      else if (code == COMPLEX_TYPE)
737
        return fold_if_not_in_template (convert_to_complex (type, e));
738
    }
739
 
740
  /* New C++ semantics:  since assignment is now based on
741
     memberwise copying,  if the rhs type is derived from the
742
     lhs type, then we may still do a conversion.  */
743
  if (RECORD_OR_UNION_CODE_P (code))
744
    {
745
      tree dtype = TREE_TYPE (e);
746
      tree ctor = NULL_TREE;
747
 
748
      dtype = TYPE_MAIN_VARIANT (dtype);
749
 
750
      /* Conversion between aggregate types.  New C++ semantics allow
751
         objects of derived type to be cast to objects of base type.
752
         Old semantics only allowed this between pointers.
753
 
754
         There may be some ambiguity between using a constructor
755
         vs. using a type conversion operator when both apply.  */
756
 
757
      ctor = e;
758
 
759
      if (abstract_virtuals_error (NULL_TREE, type))
760
        return error_mark_node;
761
 
762
      if (BRACE_ENCLOSED_INITIALIZER_P (ctor))
763
        ctor = perform_implicit_conversion (type, ctor, tf_warning_or_error);
764
      else if ((flags & LOOKUP_ONLYCONVERTING)
765
               && ! (CLASS_TYPE_P (dtype) && DERIVED_FROM_P (type, dtype)))
766
        /* For copy-initialization, first we create a temp of the proper type
767
           with a user-defined conversion sequence, then we direct-initialize
768
           the target with the temp (see [dcl.init]).  */
769
        ctor = build_user_type_conversion (type, ctor, flags);
770
      else
771
        {
772
          VEC(tree,gc) *ctor_vec = make_tree_vector_single (ctor);
773
          ctor = build_special_member_call (NULL_TREE,
774
                                            complete_ctor_identifier,
775
                                            &ctor_vec,
776
                                            type, flags,
777
                                            tf_warning_or_error);
778
          release_tree_vector (ctor_vec);
779
        }
780
      if (ctor)
781
        return build_cplus_new (type, ctor);
782
    }
783
 
784
  if (flags & LOOKUP_COMPLAIN)
785
    {
786
      /* If the conversion failed and expr was an invalid use of pointer to
787
         member function, try to report a meaningful error.  */
788
      if (invalid_nonstatic_memfn_p (expr, tf_warning_or_error))
789
        /* We displayed the error message.  */;
790
      else
791
        error ("conversion from %qT to non-scalar type %qT requested",
792
               TREE_TYPE (expr), type);
793
    }
794
  return error_mark_node;
795
}
796
 
797
/* When an expression is used in a void context, its value is discarded and
798
   no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
799
   stmt.expr/1, expr.comma/1].  This permits dereferencing an incomplete type
800
   in a void context. The C++ standard does not define what an `access' to an
801
   object is, but there is reason to believe that it is the lvalue to rvalue
802
   conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
803
   accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
804
   indicates that volatile semantics should be the same between C and C++
805
   where ever possible. C leaves it implementation defined as to what
806
   constitutes an access to a volatile. So, we interpret `*vp' as a read of
807
   the volatile object `vp' points to, unless that is an incomplete type. For
808
   volatile references we do not do this interpretation, because that would
809
   make it impossible to ignore the reference return value from functions. We
810
   issue warnings in the confusing cases.
811
 
812
   IMPLICIT is non-NULL iff an expression is being implicitly converted; it
813
   is NULL when the user is explicitly converting an expression to void via
814
   a cast.  When non-NULL, IMPLICIT is a string indicating the context of
815
   the implicit conversion.  */
816
 
817
tree
818
convert_to_void (tree expr, const char *implicit, tsubst_flags_t complain)
819
{
820
  if (expr == error_mark_node
821
      || TREE_TYPE (expr) == error_mark_node)
822
    return error_mark_node;
823
  if (!TREE_TYPE (expr))
824
    return expr;
825
  if (invalid_nonstatic_memfn_p (expr, complain))
826
    return error_mark_node;
827
  if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR)
828
    {
829
      if (complain & tf_error)
830
        error ("pseudo-destructor is not called");
831
      return error_mark_node;
832
    }
833
  if (VOID_TYPE_P (TREE_TYPE (expr)))
834
    return expr;
835
  switch (TREE_CODE (expr))
836
    {
837
    case COND_EXPR:
838
      {
839
        /* The two parts of a cond expr might be separate lvalues.  */
840
        tree op1 = TREE_OPERAND (expr,1);
841
        tree op2 = TREE_OPERAND (expr,2);
842
        bool side_effects = TREE_SIDE_EFFECTS (op1) || TREE_SIDE_EFFECTS (op2);
843
        tree new_op1 = convert_to_void
844
          (op1, (implicit && !side_effects
845
                 ? "second operand of conditional" : NULL), complain);
846
        tree new_op2 = convert_to_void
847
          (op2, (implicit && !side_effects
848
                 ? "third operand of conditional" : NULL), complain);
849
 
850
        expr = build3 (COND_EXPR, TREE_TYPE (new_op1),
851
                       TREE_OPERAND (expr, 0), new_op1, new_op2);
852
        break;
853
      }
854
 
855
    case COMPOUND_EXPR:
856
      {
857
        /* The second part of a compound expr contains the value.  */
858
        tree op1 = TREE_OPERAND (expr,1);
859
        tree new_op1 = convert_to_void
860
          (op1, (implicit && !TREE_NO_WARNING (expr)
861
                 ? "right-hand operand of comma" : NULL), complain);
862
 
863
        if (new_op1 != op1)
864
          {
865
            tree t = build2 (COMPOUND_EXPR, TREE_TYPE (new_op1),
866
                             TREE_OPERAND (expr, 0), new_op1);
867
            expr = t;
868
          }
869
 
870
        break;
871
      }
872
 
873
    case NON_LVALUE_EXPR:
874
    case NOP_EXPR:
875
      /* These have already decayed to rvalue.  */
876
      break;
877
 
878
    case CALL_EXPR:   /* We have a special meaning for volatile void fn().  */
879
      break;
880
 
881
    case INDIRECT_REF:
882
      {
883
        tree type = TREE_TYPE (expr);
884
        int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
885
                           == REFERENCE_TYPE;
886
        int is_volatile = TYPE_VOLATILE (type);
887
        int is_complete = COMPLETE_TYPE_P (complete_type (type));
888
 
889
        /* Can't load the value if we don't know the type.  */
890
        if (is_volatile && !is_complete)
891
          {
892
            if (complain & tf_warning)
893
              warning (0, "object of incomplete type %qT will not be accessed in %s",
894
                       type, implicit ? implicit : "void context");
895
          }
896
        /* Don't load the value if this is an implicit dereference, or if
897
           the type needs to be handled by ctors/dtors.  */
898
        else if (is_volatile && (is_reference || TREE_ADDRESSABLE (type)))
899
          {
900
            if (complain & tf_warning)
901
              warning (0, "object of type %qT will not be accessed in %s",
902
                       TREE_TYPE (TREE_OPERAND (expr, 0)),
903
                       implicit ? implicit : "void context");
904
          }
905
        if (is_reference || !is_volatile || !is_complete || TREE_ADDRESSABLE (type))
906
          {
907
            /* Emit a warning (if enabled) when the "effect-less" INDIRECT_REF
908
               operation is stripped off. Note that we don't warn about
909
               - an expression with TREE_NO_WARNING set. (For an example of
910
                 such expressions, see build_over_call in call.c.)
911
               - automatic dereferencing of references, since the user cannot
912
                 control it. (See also warn_if_unused_value() in stmt.c.)  */
913
            if (warn_unused_value
914
                && implicit
915
                && (complain & tf_warning)
916
                && !TREE_NO_WARNING (expr)
917
                && !is_reference)
918
              warning (OPT_Wunused_value, "value computed is not used");
919
            expr = TREE_OPERAND (expr, 0);
920
          }
921
 
922
        break;
923
      }
924
 
925
    case VAR_DECL:
926
      {
927
        /* External variables might be incomplete.  */
928
        tree type = TREE_TYPE (expr);
929
        int is_complete = COMPLETE_TYPE_P (complete_type (type));
930
 
931
        if (TYPE_VOLATILE (type) && !is_complete && (complain & tf_warning))
932
          warning (0, "object %qE of incomplete type %qT will not be accessed in %s",
933
                   expr, type, implicit ? implicit : "void context");
934
        break;
935
      }
936
 
937
    case TARGET_EXPR:
938
      /* Don't bother with the temporary object returned from a function if
939
         we don't use it and don't need to destroy it.  We'll still
940
         allocate space for it in expand_call or declare_return_variable,
941
         but we don't need to track it through all the tree phases.  */
942
      if (TARGET_EXPR_IMPLICIT_P (expr)
943
          && TYPE_HAS_TRIVIAL_DESTRUCTOR (TREE_TYPE (expr)))
944
        {
945
          tree init = TARGET_EXPR_INITIAL (expr);
946
          if (TREE_CODE (init) == AGGR_INIT_EXPR
947
              && !AGGR_INIT_VIA_CTOR_P (init))
948
            {
949
              tree fn = AGGR_INIT_EXPR_FN (init);
950
              expr = build_call_array_loc (input_location,
951
                                           TREE_TYPE (TREE_TYPE (TREE_TYPE (fn))),
952
                                           fn,
953
                                           aggr_init_expr_nargs (init),
954
                                           AGGR_INIT_EXPR_ARGP (init));
955
            }
956
        }
957
      break;
958
 
959
    default:;
960
    }
961
  expr = resolve_nondeduced_context (expr);
962
  {
963
    tree probe = expr;
964
 
965
    if (TREE_CODE (probe) == ADDR_EXPR)
966
      probe = TREE_OPERAND (expr, 0);
967
    if (type_unknown_p (probe))
968
      {
969
        /* [over.over] enumerates the places where we can take the address
970
           of an overloaded function, and this is not one of them.  */
971
        if (complain & tf_error)
972
          error ("%s cannot resolve address of overloaded function",
973
                 implicit ? implicit : "void cast");
974
        else
975
          return error_mark_node;
976
        expr = void_zero_node;
977
      }
978
    else if (implicit && probe == expr && is_overloaded_fn (probe))
979
      {
980
        /* Only warn when there is no &.  */
981
        if (complain & tf_warning)
982
          warning (OPT_Waddress, "%s is a reference, not call, to function %qE",
983
                   implicit, expr);
984
        if (TREE_CODE (expr) == COMPONENT_REF)
985
          expr = TREE_OPERAND (expr, 0);
986
      }
987
  }
988
 
989
  if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
990
    {
991
      if (implicit
992
          && warn_unused_value
993
          && !TREE_NO_WARNING (expr)
994
          && !processing_template_decl)
995
        {
996
          /* The middle end does not warn about expressions that have
997
             been explicitly cast to void, so we must do so here.  */
998
          if (!TREE_SIDE_EFFECTS (expr)) {
999
            if (complain & tf_warning)
1000
              warning (OPT_Wunused_value, "%s has no effect", implicit);
1001
          }
1002
          else
1003
            {
1004
              tree e;
1005
              enum tree_code code;
1006
              enum tree_code_class tclass;
1007
 
1008
              e = expr;
1009
              /* We might like to warn about (say) "(int) f()", as the
1010
                 cast has no effect, but the compiler itself will
1011
                 generate implicit conversions under some
1012
                 circumstances.  (For example a block copy will be
1013
                 turned into a call to "__builtin_memcpy", with a
1014
                 conversion of the return value to an appropriate
1015
                 type.)  So, to avoid false positives, we strip
1016
                 conversions.  Do not use STRIP_NOPs because it will
1017
                 not strip conversions to "void", as that is not a
1018
                 mode-preserving conversion.  */
1019
              while (TREE_CODE (e) == NOP_EXPR)
1020
                e = TREE_OPERAND (e, 0);
1021
 
1022
              code = TREE_CODE (e);
1023
              tclass = TREE_CODE_CLASS (code);
1024
              if ((tclass == tcc_comparison
1025
                   || tclass == tcc_unary
1026
                   || (tclass == tcc_binary
1027
                       && !(code == MODIFY_EXPR
1028
                            || code == INIT_EXPR
1029
                            || code == PREDECREMENT_EXPR
1030
                            || code == PREINCREMENT_EXPR
1031
                            || code == POSTDECREMENT_EXPR
1032
                            || code == POSTINCREMENT_EXPR)))
1033
                  && (complain & tf_warning))
1034
                warning (OPT_Wunused_value, "value computed is not used");
1035
            }
1036
        }
1037
      expr = build1 (CONVERT_EXPR, void_type_node, expr);
1038
    }
1039
  if (! TREE_SIDE_EFFECTS (expr))
1040
    expr = void_zero_node;
1041
  return expr;
1042
}
1043
 
1044
/* Create an expression whose value is that of EXPR,
1045
   converted to type TYPE.  The TREE_TYPE of the value
1046
   is always TYPE.  This function implements all reasonable
1047
   conversions; callers should filter out those that are
1048
   not permitted by the language being compiled.
1049
 
1050
   Most of this routine is from build_reinterpret_cast.
1051
 
1052
   The back end cannot call cp_convert (what was convert) because
1053
   conversions to/from basetypes may involve memory references
1054
   (vbases) and adding or subtracting small values (multiple
1055
   inheritance), but it calls convert from the constant folding code
1056
   on subtrees of already built trees after it has ripped them apart.
1057
 
1058
   Also, if we ever support range variables, we'll probably also have to
1059
   do a little bit more work.  */
1060
 
1061
tree
1062
convert (tree type, tree expr)
1063
{
1064
  tree intype;
1065
 
1066
  if (type == error_mark_node || expr == error_mark_node)
1067
    return error_mark_node;
1068
 
1069
  intype = TREE_TYPE (expr);
1070
 
1071
  if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
1072
    return fold_if_not_in_template (build_nop (type, expr));
1073
 
1074
  return ocp_convert (type, expr, CONV_OLD_CONVERT,
1075
                      LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
1076
}
1077
 
1078
/* Like cp_convert, except permit conversions to take place which
1079
   are not normally allowed due to access restrictions
1080
   (such as conversion from sub-type to private super-type).  */
1081
 
1082
tree
1083
convert_force (tree type, tree expr, int convtype)
1084
{
1085
  tree e = expr;
1086
  enum tree_code code = TREE_CODE (type);
1087
 
1088
  if (code == REFERENCE_TYPE)
1089
    return (fold_if_not_in_template
1090
            (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN,
1091
                                   NULL_TREE)));
1092
 
1093
  if (code == POINTER_TYPE)
1094
    return fold_if_not_in_template (convert_to_pointer_force (type, e));
1095
 
1096
  /* From typeck.c convert_for_assignment */
1097
  if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR
1098
        && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE
1099
        && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1100
       || integer_zerop (e)
1101
       || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1102
      && TYPE_PTRMEMFUNC_P (type))
1103
    /* compatible pointer to member functions.  */
1104
    return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1,
1105
                             /*c_cast_p=*/1);
1106
 
1107
  return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL);
1108
}
1109
 
1110
/* Convert an aggregate EXPR to type XTYPE.  If a conversion
1111
   exists, return the attempted conversion.  This may
1112
   return ERROR_MARK_NODE if the conversion is not
1113
   allowed (references private members, etc).
1114
   If no conversion exists, NULL_TREE is returned.
1115
 
1116
   FIXME: Ambiguity checking is wrong.  Should choose one by the implicit
1117
   object parameter, or by the second standard conversion sequence if
1118
   that doesn't do it.  This will probably wait for an overloading rewrite.
1119
   (jason 8/9/95)  */
1120
 
1121
static tree
1122
build_type_conversion (tree xtype, tree expr)
1123
{
1124
  /* C++: check to see if we can convert this aggregate type
1125
     into the required type.  */
1126
  return build_user_type_conversion (xtype, expr, LOOKUP_NORMAL);
1127
}
1128
 
1129
/* Convert the given EXPR to one of a group of types suitable for use in an
1130
   expression.  DESIRES is a combination of various WANT_* flags (q.v.)
1131
   which indicates which types are suitable.  If COMPLAIN is true, complain
1132
   about ambiguity; otherwise, the caller will deal with it.  */
1133
 
1134
tree
1135
build_expr_type_conversion (int desires, tree expr, bool complain)
1136
{
1137
  tree basetype = TREE_TYPE (expr);
1138
  tree conv = NULL_TREE;
1139
  tree winner = NULL_TREE;
1140
 
1141
  if (expr == null_node
1142
      && (desires & WANT_INT)
1143
      && !(desires & WANT_NULL))
1144
    warning_at (input_location, OPT_Wconversion_null,
1145
                "converting NULL to non-pointer type");
1146
 
1147
  basetype = TREE_TYPE (expr);
1148
 
1149
  if (basetype == error_mark_node)
1150
    return error_mark_node;
1151
 
1152
  if (! MAYBE_CLASS_TYPE_P (basetype))
1153
    switch (TREE_CODE (basetype))
1154
      {
1155
      case INTEGER_TYPE:
1156
        if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1157
          return expr;
1158
        /* else fall through...  */
1159
 
1160
      case BOOLEAN_TYPE:
1161
        return (desires & WANT_INT) ? expr : NULL_TREE;
1162
      case ENUMERAL_TYPE:
1163
        return (desires & WANT_ENUM) ? expr : NULL_TREE;
1164
      case REAL_TYPE:
1165
        return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1166
      case POINTER_TYPE:
1167
        return (desires & WANT_POINTER) ? expr : NULL_TREE;
1168
 
1169
      case FUNCTION_TYPE:
1170
      case ARRAY_TYPE:
1171
        return (desires & WANT_POINTER) ? decay_conversion (expr)
1172
                                        : NULL_TREE;
1173
 
1174
      case COMPLEX_TYPE:
1175
      case VECTOR_TYPE:
1176
        if ((desires & WANT_VECTOR_OR_COMPLEX) == 0)
1177
          return NULL_TREE;
1178
        switch (TREE_CODE (TREE_TYPE (basetype)))
1179
          {
1180
          case INTEGER_TYPE:
1181
          case BOOLEAN_TYPE:
1182
            return (desires & WANT_INT) ? expr : NULL_TREE;
1183
          case ENUMERAL_TYPE:
1184
            return (desires & WANT_ENUM) ? expr : NULL_TREE;
1185
          case REAL_TYPE:
1186
            return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1187
          default:
1188
            return NULL_TREE;
1189
          }
1190
 
1191
      default:
1192
        return NULL_TREE;
1193
      }
1194
 
1195
  /* The code for conversions from class type is currently only used for
1196
     delete expressions.  Other expressions are handled by build_new_op.  */
1197
  if (!complete_type_or_else (basetype, expr))
1198
    return error_mark_node;
1199
  if (!TYPE_HAS_CONVERSION (basetype))
1200
    return NULL_TREE;
1201
 
1202
  for (conv = lookup_conversions (basetype, /*lookup_template_convs_p=*/true);
1203
       conv;
1204
       conv = TREE_CHAIN (conv))
1205
    {
1206
      int win = 0;
1207
      tree candidate;
1208
      tree cand = TREE_VALUE (conv);
1209
      cand = OVL_CURRENT (cand);
1210
 
1211
      if (winner && winner == cand)
1212
        continue;
1213
 
1214
      if (DECL_NONCONVERTING_P (cand))
1215
        continue;
1216
 
1217
      candidate = non_reference (TREE_TYPE (TREE_TYPE (cand)));
1218
 
1219
      switch (TREE_CODE (candidate))
1220
        {
1221
        case BOOLEAN_TYPE:
1222
        case INTEGER_TYPE:
1223
          win = (desires & WANT_INT); break;
1224
        case ENUMERAL_TYPE:
1225
          win = (desires & WANT_ENUM); break;
1226
        case REAL_TYPE:
1227
          win = (desires & WANT_FLOAT); break;
1228
        case POINTER_TYPE:
1229
          win = (desires & WANT_POINTER); break;
1230
 
1231
        case COMPLEX_TYPE:
1232
        case VECTOR_TYPE:
1233
          if ((desires & WANT_VECTOR_OR_COMPLEX) == 0)
1234
            break;
1235
          switch (TREE_CODE (TREE_TYPE (candidate)))
1236
            {
1237
            case BOOLEAN_TYPE:
1238
            case INTEGER_TYPE:
1239
              win = (desires & WANT_INT); break;
1240
            case ENUMERAL_TYPE:
1241
              win = (desires & WANT_ENUM); break;
1242
            case REAL_TYPE:
1243
              win = (desires & WANT_FLOAT); break;
1244
            default:
1245
              break;
1246
            }
1247
          break;
1248
 
1249
        default:
1250
          break;
1251
        }
1252
 
1253
      if (win)
1254
        {
1255
          if (winner)
1256
            {
1257
              if (complain)
1258
                {
1259
                  error ("ambiguous default type conversion from %qT",
1260
                         basetype);
1261
                  error ("  candidate conversions include %qD and %qD",
1262
                         winner, cand);
1263
                }
1264
              return error_mark_node;
1265
            }
1266
          else
1267
            winner = cand;
1268
        }
1269
    }
1270
 
1271
  if (winner)
1272
    {
1273
      tree type = non_reference (TREE_TYPE (TREE_TYPE (winner)));
1274
      return build_user_type_conversion (type, expr, LOOKUP_NORMAL);
1275
    }
1276
 
1277
  return NULL_TREE;
1278
}
1279
 
1280
/* Implements integral promotion (4.1) and float->double promotion.  */
1281
 
1282
tree
1283
type_promotes_to (tree type)
1284
{
1285
  tree promoted_type;
1286
 
1287
  if (type == error_mark_node)
1288
    return error_mark_node;
1289
 
1290
  type = TYPE_MAIN_VARIANT (type);
1291
 
1292
  /* Check for promotions of target-defined types first.  */
1293
  promoted_type = targetm.promoted_type (type);
1294
  if (promoted_type)
1295
    return promoted_type;
1296
 
1297
  /* bool always promotes to int (not unsigned), even if it's the same
1298
     size.  */
1299
  if (TREE_CODE (type) == BOOLEAN_TYPE)
1300
    type = integer_type_node;
1301
 
1302
  /* Normally convert enums to int, but convert wide enums to something
1303
     wider.  */
1304
  else if (TREE_CODE (type) == ENUMERAL_TYPE
1305
           || type == char16_type_node
1306
           || type == char32_type_node
1307
           || type == wchar_type_node)
1308
    {
1309
      int precision = MAX (TYPE_PRECISION (type),
1310
                           TYPE_PRECISION (integer_type_node));
1311
      tree totype = c_common_type_for_size (precision, 0);
1312
      if (TYPE_UNSIGNED (type)
1313
          && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype))
1314
        type = c_common_type_for_size (precision, 1);
1315
      else
1316
        type = totype;
1317
    }
1318
  else if (c_promoting_integer_type_p (type))
1319
    {
1320
      /* Retain unsignedness if really not getting bigger.  */
1321
      if (TYPE_UNSIGNED (type)
1322
          && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1323
        type = unsigned_type_node;
1324
      else
1325
        type = integer_type_node;
1326
    }
1327
  else if (type == float_type_node)
1328
    type = double_type_node;
1329
 
1330
  return type;
1331
}
1332
 
1333
/* The routines below this point are carefully written to conform to
1334
   the standard.  They use the same terminology, and follow the rules
1335
   closely.  Although they are used only in pt.c at the moment, they
1336
   should presumably be used everywhere in the future.  */
1337
 
1338
/* Attempt to perform qualification conversions on EXPR to convert it
1339
   to TYPE.  Return the resulting expression, or error_mark_node if
1340
   the conversion was impossible.  */
1341
 
1342
tree
1343
perform_qualification_conversions (tree type, tree expr)
1344
{
1345
  tree expr_type;
1346
 
1347
  expr_type = TREE_TYPE (expr);
1348
 
1349
  if (same_type_p (type, expr_type))
1350
    return expr;
1351
  else if (TYPE_PTR_P (type) && TYPE_PTR_P (expr_type)
1352
           && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (expr_type)))
1353
    return build_nop (type, expr);
1354
  else if (TYPE_PTR_TO_MEMBER_P (type)
1355
           && TYPE_PTR_TO_MEMBER_P (expr_type)
1356
           && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type),
1357
                           TYPE_PTRMEM_CLASS_TYPE (expr_type))
1358
           && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type),
1359
                               TYPE_PTRMEM_POINTED_TO_TYPE (expr_type)))
1360
    return build_nop (type, expr);
1361
  else
1362
    return error_mark_node;
1363
}

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